Revert "Simplify SVGImage::ResetAnimation"

This reverts commit bcff0792.

Reason for revert: Speculative revert due to svg/as-image/animated-svg-wrong-timesource.html failure.
See https://ci.chromium.org/p/chromium/builders/ci/WebKit%20Linux%20Leak/8508 for first failure.

Original change's description:
> Simplify SVGImage::ResetAnimation
> 
> Now that SVGSVGElement::setCurrentTime(...) (or more specifically
> SMILTimeContainer::SetElapsed) no longer trigger further updates when
> the time container is paused, we can remove the "pending timeline
> rewind" workaround.
> When doing this also take the opportunity to fold CanScheduleFrame(...)
> in SMILTimeContainer into its only caller and simplify a little bit.
> 
> Bug: 998526
> Change-Id: I9ff3de1e8c4b28284bbf3ed27d128206ea7ee857
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1976410
> Reviewed-by: Stephen Chenney <schenney@chromium.org>
> Commit-Queue: Fredrik Söderquist <fs@opera.com>
> Cr-Commit-Position: refs/heads/master@{#726808}

TBR=pdr@chromium.org,fs@opera.com,schenney@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 998526
Change-Id: Ia0e5739e3a33d2e3c875d2f600b5f2e035701294
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980902Reviewed-by: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727236}

third_party/blink/renderer/core/svg/animation/smil_time_container.cc

@@ -397,6 +397,16 @@ void SMILTimeContainer::ServiceAnimations() {
   UpdateAnimationsAndScheduleFrameIfNeeded(Elapsed());
 }
 
+bool SMILTimeContainer::CanScheduleFrame(SMILTime earliest_fire_time) const {
+  // If there's synchronization pending (most likely due to syncbases), then
+  // let that complete first before attempting to schedule a frame.
+  if (HasPendingSynchronization())
+    return false;
+  if (!IsTimelineRunning())
+    return false;
+  return earliest_fire_time.IsFinite();
+}
+
 void SMILTimeContainer::UpdateAnimationsAndScheduleFrameIfNeeded(
     SMILTime elapsed) {
   DCHECK(GetDocument().IsActive());
@@ -404,13 +414,11 @@ void SMILTimeContainer::UpdateAnimationsAndScheduleFrameIfNeeded(
 
   UpdateAnimationTimings(elapsed);
   ApplyTimedEffects(elapsed);
-  DCHECK(!wakeup_timer_.IsActive());
-  DCHECK(!HasPendingSynchronization());
 
-  if (!IsTimelineRunning())
-    return;
   SMILTime next_progress_time = NextProgressTime(elapsed);
-  if (!next_progress_time.IsFinite())
+  DCHECK(!wakeup_timer_.IsActive());
+
+  if (!CanScheduleFrame(next_progress_time))
     return;
   SMILTime delay_time = next_progress_time - elapsed;
   DCHECK(delay_time.IsFinite());

third_party/blink/renderer/core/svg/animation/smil_time_container.h

@@ -106,6 +106,7 @@ class SMILTimeContainer final : public GarbageCollected<SMILTimeContainer> {
   void AnimationPolicyTimerFired(TimerBase*);
   ImageAnimationPolicy AnimationPolicy() const;
   bool HandleAnimationPolicy(AnimationPolicyOnceAction);
+  bool CanScheduleFrame(SMILTime earliest_fire_time) const;
   void UpdateAnimationsAndScheduleFrameIfNeeded(SMILTime elapsed);
   void ResetIntervals();
   void UpdateIntervals(SMILTime presentation_time);

third_party/blink/renderer/core/svg/graphics/svg_image.cc

@@ -99,7 +99,8 @@ class SVGImage::SVGImageLocalFrameClient : public EmptyLocalFrameClient {
 
 SVGImage::SVGImage(ImageObserver* observer, bool is_multipart)
     : Image(observer, is_multipart),
-      paint_controller_(std::make_unique<PaintController>()) {}
+      paint_controller_(std::make_unique<PaintController>()),
+      has_pending_timeline_rewind_(false) {}
 
 SVGImage::~SVGImage() {
   if (frame_client_)
@@ -515,6 +516,13 @@ sk_sp<PaintRecord> SVGImage::PaintRecordForCurrentFrame(const KURL& url) {
   // there may have been a previous url/fragment that needs to be reset.
   view->ProcessUrlFragment(url, /*same_document_navigation=*/false);
 
+  // If the image was reset, we need to rewind the timeline back to 0. This
+  // needs to be done before painting, or else we wouldn't get the correct
+  // reset semantics (we'd paint the "last" frame rather than the one at
+  // time=0.) The reason we do this here and not in resetAnimation() is to
+  // avoid setting timers from the latter.
+  FlushPendingTimelineRewind();
+
   if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled()) {
     view->UpdateAllLifecyclePhases(
         DocumentLifecycle::LifecycleUpdateReason::kOther);
@@ -557,6 +565,18 @@ void SVGImage::DrawInternal(cc::PaintCanvas* canvas,
   StartAnimation();
 }
 
+void SVGImage::ScheduleTimelineRewind() {
+  has_pending_timeline_rewind_ = true;
+}
+
+void SVGImage::FlushPendingTimelineRewind() {
+  if (!has_pending_timeline_rewind_)
+    return;
+  if (SVGSVGElement* root_element = SvgRootElement(page_.Get()))
+    root_element->setCurrentTime(0);
+  has_pending_timeline_rewind_ = false;
+}
+
 void SVGImage::StartAnimation() {
   SVGSVGElement* root_element = SvgRootElement(page_.Get());
   if (!root_element)
@@ -580,7 +600,7 @@ void SVGImage::ResetAnimation() {
     return;
   chrome_client_->SuspendAnimation();
   root_element->pauseAnimations();
-  root_element->setCurrentTime(0);
+  ScheduleTimelineRewind();
 }
 
 void SVGImage::RestoreAnimation() {

third_party/blink/renderer/core/svg/graphics/svg_image.h

@@ -210,6 +210,8 @@ class CORE_EXPORT SVGImage final : public Image {
                            const KURL&);
 
   void StopAnimation();
+  void ScheduleTimelineRewind();
+  void FlushPendingTimelineRewind();
 
   Page* GetPageForTesting() { return page_; }
   void LoadCompleted();
@@ -225,8 +227,9 @@ class CORE_EXPORT SVGImage final : public Image {
   // object size, which in turn depends on the container. One SVGImage may
   // belong to multiple containers so the final image size can't be known in
   // SVGImage. SVGImageForContainer carries the final image size, also called
-  // the "concrete object size". For more, see svg_image_for_container.h.
+  // the "concrete object size". For more, see: SVGImageForContainer.h
   LayoutSize intrinsic_size_;
+  bool has_pending_timeline_rewind_;
 
   enum LoadState {
     kDataChangedNotStarted,